The present invention relates to packaging for products, such as fresh red meat or other food products, which are enclosed between a support member and a lid in such a manner that the lid can be peelably removed from the support member or peelably delaminated to alter the gas-permeability of the lid (thereby changing the environmental conditions within the package). More specifically, the invention relates to such packaging wherein the lid has a tab to facilitate the peeling thereof.
Various forms of packaging, particularly for food products, employ a relatively rigid support member, such as a flat sheet or tray, upon or in which a product is supported. A relatively flexible lid or cover is bonded to the support member around the product, generally by forming a heat-seal between the lid and support member, to thereby enclose the product between the lid and support member. Examples of this type of packaging include vacuum skin packaging and modified-atmosphere packaging. In vacuum skin packaging, the lid is thermoformable, i.e., capable of being formed into a desired shape upon the application of heat, and is thermoformed about the product on a support member by means of heat and differential pressure. Virtually all of the air is evacuated from the interior of the package so that the lid conforms very closely to the contour of the packaged product (see, e.g., U.S. Pat. Nos. Re 30,009 (Purdue et al.) and 5,346,735 (Logan et al.), the disclosures of which are hereby incorporated herein by reference). In modified-atmosphere packaging, a food product is generally packaged in a tray-like support member having a peripheral flange to which the lid is secured. Prior to securing the lid to the support member, air is generally evacuated from the interior of the support member and replaced by a gas which extends the shelf-life of the packaged product.
In these and similar types of packaging applications, both the lid and support member generally comprise materials which form a barrier to the passage of gas therethrough so that the package is, at least initially, substantially gas-impermeable. Eventually, the lid is either completely removed from the package by the consumer or a portion of the lid is removed by a retailer prior to placing the package in a display case for consumer purchase. The latter event occurs where it is desirable to increase the gas-permeability of the lid in order to allow air (oxygen) to come into contact with the packaged product while still providing protection to the product from, e.g., dirt, dust, moisture, microbial contaminates, etc. This is generally desirable where air-contact with the packaged product renders the product more appealing to the consumer in some way.
For example, while a low-oxygen packaging environment generally increases the shelf-life of a packaged fresh red meat product (relative to meat products packaged in an environment having a higher oxygen content), red meat has a tendency to assume a purple color when packaged in the absence of oxygen or in an environment having a very low oxygen concentration, i.e., below about 5% oxygen. Unfortunately, such a purple color is undesirable to most consumers, and marketing efforts to teach the consumer about the acceptability of the purple color have been largely ineffective. When meat is exposed to a sufficiently high concentration of oxygen, e.g., as found in air, it assumes a bright red color which most consumers associate with freshness. After 1 to 3 days of such exposure, however, meat assumes a brown color which, like the purple color, is undesirable to most consumers (and indicates that the meat is beginning to spoil). Thus, in order to effectively butcher and package fresh red meat products in a central facility for distribution to retail outlets, the meat is packaged, shipped, and stored in a low-oxygen (vacuum or modified-atmosphere) environment for extended shelf-life, and then displayed for consumer sale in a relatively high-oxygen environment such that the meat is caused to "bloom" into a red color just before being placed in a retail display case.
The foregoing may be accomplished by providing a lid which peelably delaminates into a gas-permeable portion and a substantially gas-impermeable portion, with the gas-permeable portion being bonded to the support member so that the gas-impermeable portion can be peelably removed from the package. In this manner, the package may be shipped with the upper, gas-impermeable portion secured to the lower, gas-permeable portion to maintain a low-oxygen environment within the package during shipping. Then, the gas-impermeable portion may be peelably removed at the supermarket just prior to placing the package in a retail display case. Since the remaining portion of the lid is permeable to gas (oxygen), it allows the meat product to bloom in the presence of oxygen which enters the package from the ambient atmosphere. This packaging concept is also applicable to poultry, which assumes a pink color in the presence of oxygen but has a longer shelf-life in a low-oxygen environment.
Regardless of whether the lid is completely removed or peelably delaminated, it is desirable that the lid have a tab which can be manually grasped to facilitate peeling. Such a peel tab would desirably be provided without necessitating additional process or packaging steps, materials (e.g., materials from which the tab would be formed), or expense. It would also be desirable for the lid having such a peel tab to result in an aesthically appealing package both prior to peeling and, in the case where the lid is delaminatable, after peelable delamination of the lid.